Category: Dictionary

hamlet : A small human settlement, variably defined as one the size of a town, village, or parish or as a smaller subdivision of or satellite entity to a larger settlement.

hachure : Any of a series of non-numerical lines used on a map to indicate the general orientation and steepness of topographical terrain. Such lines vary in length, thickness, and spacing, with steeper slopes indicated by shorter, heavier, and more closely spaced lines

guyot: Also tablemount.

An isolated underwater seamount with a flat top that is at least 200 metres (660 ft) below the water’s surface.

gully : A landform resembling a large ditch or a small ravine created by the action of swift running water eroding deeply and sharply into soil, typically on a hillside.

gulf : A large arm or inlet of an ocean or sea that lies within a curved coastline, similar to a bay but usually larger and often with a narrower opening.

gulch: A deep, V-shaped valley formed by erosion, often containing a small stream or a dry streambed, especially one in arid regions.

groyne : A rigid, man-made hydraulic structure extending from an ocean shore or river bank, constructed to interrupt water flow and limit the movement of sediment by longshore drift.

growing season : The part of the year during which local weather conditions (i.e. temperature and precipitation) permit the normal growth of plants in a given location. What defines a “growing season” is often informal and colloquial, and may vary widely by location and from year to year; in many places, the local growing season is defined as the period of time between the average date of the last frost (in temperate parts of the Northern Hemisphere, this typically occurs in the spring) to the average date of the first frost (in the autumn).

grove : A small group of trees growing close together and generally surrounded by little or no undergrowth.

groundwater : The water present beneath the Earth’s surface in soil pore spaces and in fractures and voids within geological strata. Contrast surface water.

grid north : The direction northwards as indicated by the grid lines of a map projection, which may or may not be aligned with geodetic north. Grid north may also differ from magnetic north.

grid : A pattern of lines on a chart or map, such as those representing latitude and longitude, which helps determine absolute location.

great-circle distance: Also orthodromic distance.

A route which follows the arc of a great circle as defined by the intersection of the Earth’s surface with an imaginary plane passing through the Earth’s center. It is the shortest route between two places on the Earth’s surface.^[

great circle: Also orthodrome.

Any circle on the surface of a sphere created by the intersection of the sphere and a plane that passes through its center. A great circle divides the sphere into two equal hemispheres, and all of a sphere’s great circles have the same center and circumference as each other, which by definition is the largest possible circumference of the sphere. The mathematical properties of great circles make them useful in geodesy, where they are often visualized upon the surface of the Earth (despite the fact that the Earth is not a perfect sphere): for example, the Equator of the idealized Earth is a great circle, and any meridian with its antimeridian forms a great circle. Because the shortest path between any two points on the surface of a sphere follows the arc of a great circle, great-circle distances are often used as approximations of geodesics for the purposes of air and sea navigation.

graticule : A network of lines on a map or chart (or imagined on the surface of the Earth) representing geodetic parallels of latitude and meridians of longitude

graben : A depression or valley bounded on either side by distinct, parallel escarpments or faults and formed by the downward displacement of a block of the Earth’s crust. Grabens often occur side-by-side with horsts, their uplifted or non-displaced counterparts, in a repeated series of vertical displacements.

gnamma See panhole.

globalization : The process of interaction and integration among people, companies, governments, and cultures across the world. A complex and multifaceted phenomenon, globalization is considered largely the result of economically motivated advances in transportation and communication technologies in the past several centuries which have dramatically increased interactions between otherwise isolated groups of people.

Global Positioning System (GPS) : A satellite-based radionavigation positioning system owned and operated by the United States Department of Defense and made available for use by both the military and the general public. It is one of several GNSS standards that provides geolocation and time information, transmitted via microwave signals, to enabled satellite navigation devices, known as GPS receivers, anywhere on or near the Earth where there is an unobstructed line of sight to at least four GPS satellites. Modern state-of-the-art GPS receivers can accurately pinpoint locations to within 30 centimetres (0.98 ft).

global city : Also world city, power city, or alpha city.

A city which functions as an important or primary node in the global economy. Though criteria are not strictly defined, a global city typically is very large; dominates trade and economic interactions within a large surrounding area; supports a large and demographically diverse population; serves as a center of ideas and innovation in business, science, culture, and politics; and/or is a headquarters for major financial institutions, multinational corporations, or worldwide media and communications networks.

glen : A long valley bounded by gently sloping, concave sides, and typically narrower and deeper than a strath. The term is used primarily in Scotland.

glade: Also clearing.

Any large, open, mostly treeless area within a forest.

glacier : A persistent mass of dense ice that is constantly moving under its own weight, and which is composed largely of compacted snow that forms where the annual accumulation of snow exceeds its melting and sublimation over very long periods of time. Glaciers slowly deform and abrade the land beneath them, creating a huge variety of landforms including cirques, moraines, and fjords. They form exclusively on land and are distinct from the much thinner ice that forms on bodies of water.

glaciation : 1.  The process or state of being covered with a glacier.

2.  Another name for a glacial period, an interval of time that is marked by colder temperatures and advancing glaciers.

glacial till: The mass of rocks and finely ground material carried by a glacier and deposited when the ice melts. This creates an unstratified material of varying composition.

ghetto : A section of a city occupied by members of a minority group who live there because of social restrictions on their residential choices. Originally, the term referred specifically to a section of a European city to which Jews were confined

geostatistics : A branch of statistics which involves the organization, management, and analysis of spatial and spatiotemporal datasets. Geostatistical algorithms are often incorporated in GIS software applications.

geosphere : The collective non-living parts of the Earth: the lithosphere, the atmosphere, the cryosphere, and the hydrosphere

geoscience : See Earth science.

geomorphology : The study of the arrangement and form of the Earth’s crust and of the relationship between these physical features and the geologic structures beneath

geomatics: Also geospatial science.

The scientific discipline that involves gathering, storing, processing, and delivering geographic or spatially referenced information.

geolocation : The identification or estimation of the real-world geographic location of an object, involving the generation of a set of geographic coordinates in order to determine a more meaningful description of location, such as a street address.

geoinformatics : The science and technology which develops and uses information science infrastructures to address problems and analyze data within geography, cartography, geoscience, and related branches of science and engineering.

geoid : The shape that the surface of the Earth’s oceans would take under the influence of Earth’s gravity and rotational acceleration alone, in the absence of other influences such as winds and tides. It is often characterized as the precise mathematical figure of the Earth: a smooth but irregular gravitational equipotential surface at every point of which, by definition, the direction of the force of gravity is always perpendicular and spirit levels are always parallel. Its shape results from anomalies in the Earth’s gravitational field caused by the uneven distribution of mass within and on the Earth’s surface. A reference ellipsoid is an idealized approximation of the more complex and accurate geoid.

geography : The scientific study of the lands, features, inhabitants, and phenomena of Earth.

geographical mile : A unit of length defined as the distance equal to one minute of arc along the Earth’s Equator: approximately 1,855.3 metres (1.1528 mi; 1.8553 km). The precise length varies with the reference ellipsoid used to approximate the shape of the Earth. Regardless of the particular ellipsoid, the length of one degree of longitude at the Equator is equal to exactly 60 geographical miles.

Geographic Names Information System (GNIS) : A digital public-domain database developed by the U.S. Geological Survey and the U.S. Board on Geographic Names which contains name and locative information about more than two million physical and cultural features located throughout the United States and its territories. Each feature recorded in the database receives a unique feature record identifier called a GNIS identifier.

geographic information system (GIS): Any system of computer software tools designed to allow users to record, store, manipulate, analyze, manage, and present large sets of spatial or geographic data.

geographic information science (GIS): Also GIScience.

The scientific study of data structures and computational techniques for capturing, representing, processing, and analyzing geographic information.

geographic coordinate system: A coordinate system used in geography that enables every location on Earth to be specified by a set of numbers, letters, or symbols. Geographic coordinates are often chosen such that one of the numbers represents a vertical position such as elevation and two or three other numbers represent a horizontal position such as latitude and longitude.

geodynamics: A subfield of geophysics and Earth science that studies the physical dynamics of the Earth by applying physics, chemistry, and mathematics to the understanding of how mantle convection and other internal processes lead to plate tectonics and geological phenomena such as mountain formation, volcanism, earthquakes, and faulting, among others.

geodetic datum: Also geodetic system, geodetic reference datum, or geodetic reference system.

A coordinate system and set of reference points used for locating places on the Earth, which defines horizontal and vertical coordinates upon a particular reference ellipsoid that approximates the figure of the Earth. Geodetic datums are used in geodesy, navigation, and surveying applications to translate positions indicated on paper or digital maps to their actual positions on the Earth; because the Earth is an imperfect ellipsoid, localized datums such as the ED50 covering only specific countries or regions are often more accurate representations of their area of coverage than global standards such as the WGS 84 of the World Geodetic System.

geodetic control network: Also geodetic network, reference network, or control point network.

geodesy: Also geodetics.

The science of accurately measuring and understanding the Earth’s geometric shape, orientation in space, and gravitational field and how these properties change over time.

gazetteer : A geographical dictionary or directory used in conjunction with a map or atlas and containing information concerning the geographical make-up, social statistics, and physical features of a country, region, or continent.

functional diversity : The characteristic of a place where a variety of different activities (economic, political, or social) occur, most often associated with urban places.

fresh water : Any naturally occurring water characterized by low concentrations (typically less than 0.05% by volume) of dissolved salts and other solids relative to either salt water or brackish water. Sources of fresh water on Earth include glaciers, ice caps, icebergs, bogs, lakes, rivers, streams, and most groundwater.

forest : Any extensive area dominated by communities of trees.

footslope : The part of the profile of a hillslope that forms the concave surface at the base of the slope. It is a transition area between sites of erosion and transport higher up the slope (e.g. the shoulder and backslope) and sites of deposition further down the slope (the toeslope).

foothills : A geographic transition zone defined by gradual increases in elevation between plains or low-relief hills and adjacent topographically higher hills, mountains, or uplands.

focus: Also hypocenter.

The point inside the Earth’s crust from which an earthquake originates.

fluvial : Of or pertaining to rivers or streams; produced by the action of a river or stream

focality : The characteristic of a place that follows from its interconnections with more than one other place. When interaction within a region comes together at a single place (i.e. when the movement focuses on that location), the place is said to possess focality.

floodplain: Also bottomland.

A broad, flat area of land adjacent to a river or stream which is leveled by annual flooding and by the lateral and downstream movement of meanders.

fjord: Also fiord.

A long, narrow marine inlet with steep sides or cliffs created by glacial erosion.

fissure : A long, narrow opening or line of breakage made by cracking or splitting, especially in rock or earth

fish ladder : A series of shallow steps down which water is allowed to flow, designed to permit salmon or other anadromous fish to circumvent artificial barriers such as dams as they swim upstream to spawn

firth : Another name for a coastal inlet, strait, or bay associated with the mouth of a large river, where the tidal effects of seawater passing upriver have widened the riverbed into an estuary. The term is used primarily in Scotland.

firn : A type of ice that is at an intermediate stage between snow and glacial ice. More specifically, firn is partially compacted névé left over from past seasons which has subsequently recrystallized into a form that is harder and denser than névé.

figure of the Earth : The size and shape of the Earth as studied in geodesy. Applications requiring varying levels of precision have led to the development of many different models of the Earth, ranging from simple spheres to much more accurate approximations such as geoids.

field: Also spatially dependent variable.

A quantity or observation, such as temperature, soil moisture, or population density, that can be theoretically assigned to any point of space. Both scalar and vector fields are found in GIS applications, although the former is more common.

federation : A form of government in which powers and functions are divided between a central government and a number of political subdivisions that have a significant degree of political autonomy.

fault zone : An area of numerous fractures in the Earth’s crust along which movement has occurred. The movement may be in any direction and involve material on either or both sides of the fractures

fault-block mountain : A mountain mass created by either the uplift of land between faults or the subsidence of land outside the faults.

fault : A fracture in the Earth’s crust accompanied by a displacement of one side of the fracture

fallow : Agricultural land that is plowed or tilled but left unseeded during a growing season. Fallowing is usually done to conserve moisture and soil nutrients

fall line : A geomorphologic unconformity between an upland region of relatively hard crystalline basement rock and a coastal plain of softer sedimentary rock.

exurban : An adjective describing a region or district that lies outside a city and usually beyond its suburbs; a place of this type is called an exurb. Compare rural

extinct volcano: A volcano that is not expected to erupt again.

exotic stream : A stream found in an area that is too dry to have spawned such a flow. The flow originates in some moister section.

exclave : A portion of a state or territory that is geographically separated from the main part by surrounding foreign territory of one or more other states or political entities. Many exclaves are also enclaves.

evorsion : See pothole.

evapotranspiration : The process by which water is lost from an area through the combined effects of evaporation from the ground surface and transpiration from vegetation.

etchplain : A plain beneath which the bedrock has been subjected to considerable subsurface weathering, known as “etching”. Erosion of the regolith overlying an etchplain often exposes topographical irregularities such as inselbergs.

estuary : The broad lower course of a river where it enters the ocean and is affected by the tides. Compare delta

esker: Also called an os or spelled eskar or eschar.

A long, winding ridge of stratified sand and gravel, usually occurring in glaciated or formerly glaciated areas.

escarpment : A long cliff or steep slope separating two comparatively level or more gently sloping surfaces and resulting from erosion or faulting.

erratic : A boulder that has been carried from its source by a glacier and deposited as the glacier melted. Such boulders are often of different rock types than the surrounding rocks.

Equator : The imaginary circle around the Earth halfway between the geographic poles which is assigned a latitude of zero degrees and is therefore used as a reference point for all other lines of latitude. It is the largest circumference of the Earth

epicenter : The point on the Earth’s surface directly above the focus of an earthquake, near which the seismic waves produced by the earthquake are usually most noticeable.Equator

endorheic basin : A closed drainage basin that allows little or no outflow to external bodies of water but converges instead into internal lakes or swamps which equilibrate through evaporation.

enclave : A tract or territory completely surrounded by and enclosed within the territory of one other state, country, or other political entity. Unlike enclaves, exclaves can be surrounded by more than one other state

emergent coastline : A coast or shoreline resulting from a rise in land surface elevation relative to sea level

ekistics: The scientific study of human settlements of all types, incorporating concepts such as regional, metropolitan, and community planning and dwelling design with the goal of achieving harmony between the inhabitants of a settlement and their physical, social, and cultural environments.

elevation : The height of a point on the Earth’s surface with respect to sea level. Compare altitude.

edgelands : The transitional areas of “fringe” space at the boundaries of a country, city, or other artificial geographical entity, often distinguished by a partly man-made, partly natural landscape that is in the earliest stages of human management and organization. Compare hinterland.

edge city : A concentration of businesses, commercial buildings, or retail and entertainment venues situated outside of a traditional downtown or central business district in what was previously a suburban residential or rural area.

ecoregion: Also called an ecological region.

A type of biogeographic province that is smaller than a bioregion and which contains characteristic, ecologically and geographically distinct, and relatively uniform assemblages of biological communities and species. Ecoregion boundaries often overlap within ecotones and mosaic habitats, and most ecoregions contain habitats that differ from those described for their assigned biome.

economies of agglomeration : The economic advantages that accrue to an activity by locating close to other activities; benefits that follow from complementarity or shared public services

economic geography : A sub-discipline of geography which studies the location, distribution, and spatial organization of economic activities across the world.

Eastern Hemisphere : The half sphere of the Earth that is east of the Prime Meridian and west of the antimeridian. It is opposite the Western Hemisphere.

earthquake : The sudden and intense shaking of the ground due to tectonic activity.

Earth science: Also called the Earth sciences or geoscience.

1.  A collective term for the various fields of natural science related to the planet Earth.2.  The branch of science that studies the physical constitution and characteristics of the Earth and its atmosphere, using methods and tools from geography, geology, physics, chemistry, biology, and mathematics to build a quantitative understanding of how the Earth works and changes over time.

dune : A hill of loose sand built by the movements and erosional and depositional processes of wind or water, often occurring in deserts and coastal areas.

dry point : An area of firm or dry ground in a wetland, marsh, or floodplain, often capable of supporting a human settlement.

dry farming : A type of farming practiced in semi-arid or dry grassland areas without irrigation using such approaches as fallowing, maintaining a finely broken surface, and growing drought-tolerant crops.

drumlin : An elongated hill in the shape of an inverted spoon or half-buried egg which is formed by glacial ice acting on underlying unconsolidated till or ground moraine.

draw: Also re-entrant.

1.  A terrain feature formed by two parallel ridges or spurs with low ground in between them.2.  Another name for an arroyo, ravine, or gulch, especially one with a broad floor and gently sloping sides.^[